1. Field of the Invention
The present invention relates to a multi-core cable in which a plurality of pair cables are shielded altogether with an overall shielding tape.
2. Description of the Background Art
A pair cable consisting of electrically insulated two signal conductors is well known as signal wires for transmitting high-speed digital signals. The method of transmitting signals using a pair cable is called differential signaling. It allows a signal to be output twice on the receiving side, since signals whose phases are reversed by 180 degrees are input into two signal conductors respectively at the same time and transmitted and the difference of the signals are read at the receiving side. Also, such transmission exhibits a noise removal feature because the noise given during signal transmission is equally given to the two signal conductors and hence canceled when it is output as a differential signal at the receiving side. Pair cables are used for wiring in electronic equipment and vehicles in a form of a multi-core cable in which a plurality of pair cables are assembled. (Hereinafter, a pair cable contained in the multi-core cable is called a “core cable”.)
Japanese Patent Application Publication No. H8-241632 (Patent document 1) discloses a multi-core cable in which twisted pair cables are adopted as core cables. In this multi-core cable, a plurality of core cables are stranded together to make a core unit and an insulation tape is spirally wrapped in an overlapping manner as an inner sheath layer around the outer circumference thereof, and thereafter a metal foil tape is wrapped as a shielding layer thereover, and further a sheath layer is provided overall by extrusion. Patent document 1 does not mention either a direction in which a plurality of core cables are to be stranded together, nor wrapping direction of the insulation tape or the metal foil tape.